How to Tighten a Bike Chain (Updated 2021)

*Please note that this post may have affiliate links. By clicking on them, we may get a small commission on any sale.

If you use your bike regularly you will experience a loose or detached chain from time to time. It doesn’t mean that there’s anything wrong with the bike. With the right tools, you can quickly learn how to tighten a bike chain.

A bike chain is a crucial component of any bicycle. When you pedal, it transfers power to the wheels allowing you to move forward. When it’s loose, the rate of power transfer drops, and you aren’t able to propel the bike forward.

A bike chain can fall off completely, but oftentimes it only becomes loose. If it isn’t too loose, you can keep cycling until your destination and then tighten it.

This article will take you through a step by step on how to tighten a bike chain on a single gear bike, and how to tighten a bike chain with gears. It will also answer some frequently asked questions about bike chains and how to tighten them.

How to tighten a bike chain

#1. How to Tighten a Bike Chain on a Single Gear Bike

If you are completely new to bikes you may wonder what a single gear bike is. It is a type of bike that has only one gear; instead of a freewheel mechanism in the rear wheel, it has a cog. When you cycle, the cog turns and then the wheels turn.

It is what is commonly known as a fixie. You can learn more about fixies in my article, Ultimate Guide to Types of Bicycles.

Fixie bikes are best used by those who want to incorporate a bit of a workout in their cycling. For every inch of ground you cover, you have to put your legs into it. It’s a great way to get in shape or practice for a cycling event.

Fixed gear Bikes

How to tighten a loose chain on a fixie

You’ll need the following tools:-

A Bike Repair Tool Kit is ideal and highly recommended.

Step 1: Put your bike in the correct position

If you are highly experienced with the process of tightening a bike chain you can do it with the bike standing right-side-up, but I highly recommend that you turn your bike over so that you can access the parts easily.

Place your bike upside-down on the bike stand, with the wheels in the air and the saddle on the stand. If you don’t have a bike stand you should lay out a soft surface (like a piece of a cardboard box or a layer of newspapers) so that you don’t scratch the saddle.

Step 2: Loosen the rear axle

In order to be able to adjust the chain so you need to remove the nuts that hold the tire to the bike. For this, use a socket wrench and carefully turn the nuts in an anti-clockwise motion until they come loose.

Step 3: Pull back on the rear tire

This is where you will increase the tension in the chain. Carefully pull back on the rear tire until you get the desired tension in the chain.

This process should be done very slowly, as any quick movements can snap the chain. As you pull back, check the tension and keep going until you have the desired tightness. You should be able to move the chain both ways at least half an inch.

Make sure that the tire remains centered in the wishbone so that tightening it back is easy.

Step 4: Make sure that you have the right chain tension

I’ve already mentioned that the chain should be able to move half an inch in either direction, but I would like to talk about it a little more. As you pull the tire back the chain tension will change – you can feel it as you work.

If it moves too far in either direction it means it isn’t tight enough and should be pushed a bit more on the tire.

If it’s too tight you will not be able to turn the pedals, so it’s important to make sure that you get this step just right.

*Check out Tips on How to Clean a Chain on a Bike

Step 5: Tighten the rear tire back into place

If you’re happy with the chain tension it’s time to lift the rear tire back into place and replace the axle nuts. One at a time, replace each and using the socket wrench make sure that they are all tight enough.

The tire must be properly fitted back onto the frame. When it’s securely in place it shouldn’t touch the bike frame or the chain.

Step 6: Test the chain and the tire

Test the chain by moving it a little in both directions; it should move with ease half an inch both ways. Spin the tire to make sure that it’s moving properly and doesn’t come in contact with the chain or the frame whilst in motion (if it does it means you’ve fitted it back wrong and you need to repeat the process).

Your chain is tight once more, and your fixie is ready for the road!

*Learn How to Remove Rust from Bike Chain

#2. How to Tighten a Bike Chain with a Derailleur

When the chain comes off a fixie it hangs but doesn’t really pose much of a hazard. However, a loose chain on a multi-gear bike can pose real danger as your foot can get caught in it and lead to serious injury.

If you notice that the chain on your multi-gear bike is loose you should get off right away and walk to the nearest place where you can fix it.

If you have the right tools and you know the steps you can fix it right there. Here’s what you need to do:

Step 1: Put the bike in the correct position

Flip the bike upside down onto a bike stand so that the tire and derailleur are within your reach. If you don’t have a bike stand you can find a soft surface that doesn’t scratch the saddle and handlebars.

Step 2: Locate the derailleur screw

On multi-gear bikes, at the back of the derailleur, there is a screw. On most bikes, you’ll find the letter B, and next to it will be the screw. To increase the tension on the bike chain you’ll need to turn this screw clockwise in a tightening motion.

How to adjust a bike chain with a derailleur

Step 3: Access and adjust the rear tire

To do this you need to disconnect the brakes from the cable, so lift the brake lever and then raise it so that you have access to the rear tire.

Step 4: Adjust the rear tire

To increase tension on the chain of a derailleur, slide the wheel axle toward the rear dropouts making only small adjustments as you go along – you don’t want the chain to become too tight.

For each adjustment lower the brake lever and check if you have enough chain tension. If not, lift the lever and continue to make adjustments until you’re happy with the result.

Step 5: Put everything back together

Once you feel that you have enough chain tension you should put everything back together just as it was and make sure that the derailleur screw is properly fitted and tight enough.

Check that the tire is spinning properly and doesn’t come in contact with the bike frame or the chain itself.

If you aren’t happy with the tension, repeat the process.

All this may seem tedious, but after doing it once or twice you will become a natural. Make sure to wear gloves to protect your fingers and keep a rag handy to wipe away lube as you work.

Bike chain tension: Frequently Asked Questions

  • What causes my bike chain to become loose?

Even if you maintain your bike on a regular basis the chain will come loose from time to time. It can happen for a number of reasons.

One of the most common is a new chain on an old bike.

When you put a new chain on a bike whose parts have worn away it doesn’t fit exactly. It jumps around when the tires move and will eventually become loose or come off completely. If this happens don’t fret; just tighten the chain using the steps outline here and with a little use it will fit properly in the cog and stop coming loose.

A very old chain will also come loose; it has been worn so smooth by motion that it doesn’t fit properly in the cogs anymore. For such a chain, the only remedy is a replacement.

Loose nuts on the rear axle can also cause problems, as they shorten the distance between the pedals and the wheel.

On multi-gear bikes, derailleur damage can be the cause of the problem. If you find yourself having to tighten your chain frequently on this type of bike you ought to check if the derailleur is bent or has dents.

  • How tight should a bike chain be?

It should move about half an inch in either direction. If you tighten your bike chain using the steps outlined here but it still has some slack it means that the chain itself has expanded; over time the links can grow longer, so you may need to remove a few to achieve the right amount of tension.

  • Does lubricating the chain affect its tension?

Yes; if you don’t clean and lubricate the chain on a regular basis it will soon rust and wear away, and it will become slack more often. A well-lubricated chain makes it easier to ride your bicycle and also maintains the chain for longer.

For more on bike chain lubrication please read How to Clean a Chain on a Bike and How to Remove Rust from Bike Chain.

  • Are there easier ways of tightening a bike chain?

If you are not the DIY sort no doubt the process of how to adjust bike chain tension must seem complicated and time-consuming.

Unfortunately, there aren’t any shortcuts. If the chain on your bike becomes loose, whether it’s a fixie or a derailleur these are the steps that will correct the problem.

However, you don’t have to do it yourself. You can identify a reliable bike shop near you that can do proper maintenance at least once a month. Not only will they clean and oil the chain, but they will also check the tension, and if it’s slack, make the necessary adjustments.

  • What’s better? to tighten the chain or replace it?

It depends; if the chain becomes loose because it’s old then it’s time for you to replace it. Replacement chains for most bike models are affordable and can help extend the life of the bike.

However, if the chain is relatively new you shouldn’t buy a new one. Just tighten it and the bike should be good to ride once more.

Summary

It is quite normal for a bike chain to become loose or even fall off, so you shouldn’t panic if it happens. You can put it back and adjust the tension with the steps outlined in this article.

Keep in mind that the process for tightening a bike chain on a single-gear bike is different from that of a multi-gear bike.

Different types of bikes are built differently and the process may change slightly. If you aren’t sure what to do refer to the manufacturer’s guidebook or get directly in touch with them so that they can send you instructions for your specific type of bike.

Alternatively, you can have the chain tightened at a reliable bike shop that has experience with your type of bike.

Best handheld ham radio